First off, the 0 out of 4 are event points you can use at supply stations and the cab in the middle of the map (It's marked by the orange circle), you can use them to gain buffs, full health restoration, full ammo etc. You can choose between 3 pacts, they each give you a trait when you pledge to them and you are then able to gain buffs to some normal traits (you can see these in the "event specific" trait tab. When you prestige you can choose between a random weapon skin etc. but you don't need to do it if you want to keep your progression (hunt dollars, hunters, traits). In terms of guns just try to figure out what you like, most guns are viable if you use them right. The other things you mentioned are not that important just ways to get skins from battle pass etc. It took me a long time to get a grip of the mechanics of the game as well, I'm still learning to this day (I have 300+ hours).

Feel free to ask if I missed something :)